Froth flotation of sulfide minerals with di-alkyl thiophosphoryl chlorides



Patented Dec. 16, 1952 FROTH FLOTATION OF SULFIDE MINERALS WITH DI-ALKYL THIOPHO SPH O R/YLv CHLORIDES Robert B. Booth, Stamford, and Charles L. Morris, f J r., Noroton Heights, Conn., assignors to American Cyanamid Company, New York, N. Y., a

corporation of Maine No Drawing. Application October 4, 1950, Serial No. 188,478

This invention relates to an improved method of froth flotation of sulfide ores using a new type of reagent.

The standard methods of floating sulfide ores I involve the use of two principal types of reagent. The first are the various xanthates; and the second, esters of dithiophosphoric acid. While these reagents are extremely effective in most sulfide notations and account for the large bulk of sulfides recovered by froth flotation, they are less effective especially in certain circuits, 1. e. those which are strongly acid. For this special type of froth flotation, there have been developed special promoters or collectors in which Xanthates are condensed with various other compounds. Among the most commonly used constitute reaction products of various chloroformates with xanthates of which ethyl xanthogen ethyl formate is one of the most efficient. While the special condensed xanthate reagents have enjoyed marked success in special acid circuit flotations, they still leave something to be desired in recovery.

' The present invention utilizes a new type of flotation promoter or collector, namely dialkyl thiophosphoryl chlorides. This is an unusual type of reagent because generally promoters are used in the form of free acids or salts. The reactivity of acid chlorides is normally so great that such compounds could not be considered practical for froth flotation because of instability. It is not known Why the dialkyl thiophosphoryl ohloridesof the present invention are so stable, particularly in the acid circuits in which they are used and it is not desired to limit the present invention toany theory of why these acid chlorides should exhibit such an abnormal stability. The reagents of the present invention may be represented by the following type formula:

in which R and R are alkyl radicals.

When the reagents of the present invention are used, substantial increases in recovery are obtained over former reagents and in some favorable circumstances giving recoveries approaching quantitative.

The efiiciency will vary somewhat with difierent members of the series. In general, however, they appear to give improved results over the standard reagents hitherto used. Sulfide flotations which give high recoveries, even with standard reagents, present an important economic problem because many of the ores, such as copper ores, have only one to two percent of copper andlncreases in. recovery make very substantial cost savings.

14 Claims. (Cl. 209-166) It is an advantage of the present invention that any of the ordinary alkyl groups may be present in the promoter. The cheapest alkyl thiophosphoryl chlorides are those in which the alkyl groups are the same, and as these compounds are just as eflicient as those in which the alkyl groups are different, they are preferred. However, the invention is not limited thereto and mixed compounds may be used where R is an alkyl group and R is a different one. Typical of such compounds are methyl, ethyl, ethyl isopropyl, etc.

Many of the alkyl thiophosphoryl chlorides are obtainable in relatively pure form. however, necessary to use highly purified compounds and crude products give reasonably satisfactory results and, in some cases, represent an economical advantage.

The invention will be described in greater detail in conjunction with the following specific examples. It is to be understood that these examples are set forth for the purpose of illustration only and are not t be considered as limitations on the case, except as indicated by the appended claims.

Example 1 A South American copper ore (about 1.9-2.0% Cu) was ground in separate tests with various dialkyl thiophosphoryl chlorides to minus mesh and then conditioned with 8.0 l6/ton sulfuric acid and 0.24 l6/ton cresylic acid. The resulting pulp was floated in a Fagergren flotation machine at 22% solids for 7.5 minutes. A comparative test was carried out with ethyl xanthogen ethyl formate added to the grind; this material is the standard promoter for this ore. The following metallurgical results were obtained:

A copper-bearing slime from the northwestern part of the United States minus 325 mesh; about 1.6-l.'7% Cu in copper content) was con- It is not,

3 ditloned with 0.2 16/ton of diethyl thiophosphoric --chloride and 0.13 16/ton pine oil and floated in a Fagergren flotation machine for 6 minutes. A concentrate, assaying 7.01% Cu and containing 84.3% of the total copper was obtained; the tailings assayed 0.14% Cu.

A corresponding test with 0.2 16/ton of ethyl xanthogen ethyl formate recovered 80.0% of the copper in a concentrate assaying 625% Cu; the tailing assayed 0.26% Cu.

Example 3 Diethyl thiophosphoryl chloride and diisopropyl thiophosphoryl chloride were used also as promoters on a zinc ore from the southeastern part of the United States. This ore was ground to about 65 mesh and conditioned with 0.075 lb./ton of each promoter and 0.065 lb./ton pine oil as frother. The resulting pulp was floated in a "Fagergren fiotation machine for 5 minutes. I

The metallurgical results were as follows:

Concentrate l Tailiug- Promoter U seal i For Per Cent Zn Per Cent I Cent Zn Assay I Assay Becov.

Diethyl thiophosphoryl chloride 64 43. Q9 97. 51 0. 07 Diisopropyl thiophosphoryl chloride 2. 61 L7. 00 90. 74 0.09

4 3. A method according to claim 2 in which the promoter is dimethyl thiophosphoryl chloride.

4. A method according to claim 1 in which the ore is a copper sulfide ore and the promoter is .diethyl thiophosphoryl chloride.

5. Amethod according to claim 1 in which the ore is :a copper sulfide ore and the promoter is diisopropyl thiophosphoryl chloride.

.6. A'method according to claim 1 in which the ore is a copper sulfide ore and the promoter is di-sec. ibutyl thiophosphoryl chloride.

7. A method according to claim 1 in which the .ore :is a zinc sulfide ore.

--8. A method according to claim '7 in which the promoter is diethyl thiophosphoryl chloride.

9. A method according to claim 1 in which flotation is efiected in acid circuit.

'10. A method according to claim 9 in which the sulfide ore is a copper sulfide ore.

11. .A method according .to claim 10 in which the promoter is :dimethyl thiophosphoryl chloride.

12.. A method according to claim9 in which the flotation is effected in acid circuit, the ore is a copper sulfide ore and the promoter is diethyl thiophosphoryl chloride.

13. A method'according to claim 9 in which the flotation is effected in acid circuit, theore is a copper sulfide .ore and the promoter is diisopropyl thiophosphoryl chloride.

'14. A method according to claim?) in which the flotation is effected in .acid circuit, the ore is a copper sulfide ore and the promoter .is di-sec. :butyl thiophosphoryl chloride.

vlilOBERT B. BOOTH. CHARLES L. MORRIS, .JR.

REFERENCES CITED The following references .are of record in the file .of this patent:

UNITED STATES PATENTS Number Name Date -1;8-12, 839 Derby June 30, 1931 1,893,018 Christmann Jan. 3, 1933 2,482,063 Hechenble'ikner Sept. 13, 1949 

1. A METHOD OF BENEFICIATING SULFIDE ORES BY FROTH FLOTATION WHICH COMPRISES EFFECTING THE FROTH FLOTATION IN THE PRESENCE OF A PROMOTER HAVING THE FOLLOWING FORMULA: 